An immunoprecipitation method to detect gonococcal surface protein antigens was devised. This method along with immunoblotting was used to study the comparative antigenicities of protein III and protein II consituents of gonococci. For all strains examined, protein III moieties appeared antigenically identical. This confirms other studies in this lab in which identical 125I-peptides were found for all protein III constituents from diverse strains (Judd, report Z01 AI 00237-01 LMSF). On the other hand, protein(s) II generally were entigenically distinct whenassayed either by immunoprecipitation (with polyspecific or monospecific sera) or immunoblottig (with polyspecific sera). However, high degrees of antigenic relatedness were found for all protein(s) II when assayed by immunoblotting with monospecific sera raised against detergent-solubilized, isolated protein II material. These studies suggest that gonococci are capable of presenting a bevy of antigenic facades to their human host during gonococcal infections.